The present invention relates generally to diesel fuel injection systems and relates more particularly to a diesel fuel injection system for use with fuels which are abrasive in nature such as coal-water slurry, and heavy oil fuels.
The use of the above so-called alternate fuels has previously been confined essentially to external combustion applications, such as the heating of boilers in power generation stations or for marine propulsion systems. The use of these alternate fuels in internal combustion engines such as large stationary diesel engines has not heretofore been feasible since the abrasive character of these fuels would be incompatible with the fuel injection system components, particularly the fuel injection pump. These components are precision machined to close tolerances in view of the high fuel pressures generated during the injection intervals. The increasing cost of diesel fuel has, however, resulted in renewed interest in the utilization of such alternate fuels as coal-water slurry and heavy oils in internal combustion engines despite the greater difficulties involved in charging an engine with such fuels.
Mechanical engine driven diesel fuel injection pumps of the reciprocating plunger type, known as jerk pumps, have long been used in diesel engines of a wide range of sizes to produce timed, metered pulses of diesel fuel to nozzles through high pressure injection lines. The injection nozzles are typically spring loaded and open automatically upon delivery of the high pressure pulses from the injection pump to introduce a spray of fuel to an engine cylinder through spray orifices. Such nozzles close sharply to terminate injection when the fuel pressure drops below the valve closing pressure. The present invention takes advantage of the well developed technology of the diesel fuel injection pumps and nozzles and the commercial availability of such equipment in sizes suitable for use with large diesel engines in providing a system suitable for use in the injection of alternate fuels.